Protective cooling system for thermionic apparatus



Dec. 19, 1933. M. A. AcHEsoN PROTECTIVE COOLING SYSTEM FOR THERMIONIC APPARATUS Filed Deo. 27, 1928 FTQ Inventor: marcus A. Acheson MMM 'H His Attorney.

' cent portionbf the cathode. It is thereiorenec-V essary toprovide a means for cooling the pinch` Patented Dec. 19, 1933 1,940,28523 i Y' rRorEC'rlvn COOLING, SYSTEM. Fon

o l THEM/uomo APPARATUS e Marcus, A. Acheson, Schenectady; N'. YL, assigner 5 to General Electric-"Company, af'corporation of New-York The present invention relates to a powertube equipment, moreiparticularlytov a protective sys; tem for ensuring the` applicationof a cooling fluid to `the various heated vparts of a therinionic device during operation.. f t p i In the operation offtransinitter tube apparatus', it'hasbeen found that. whenthe stem, through which the filament leading-in conductors pass,v

tends to become heated, fissures may form Ain the pinch seal and the vacuum fail.v This .con-

" dition is due, in some, measure, to the'ifact'that theA heat produced in these conductorsjbycm-k rent owis more orless confined bythe cylinf drical glass wall forming the reentrant stem andi alsocdueto theheat radiated Vby the incandesseal and in the past it has been customary toinsert a rubber tubing into thereentrant sternin;`

sucha manner that a .cooling Vfluid maybe dii rected. against the leading-in conductors and `the pinch seal.r However, as a practical matter, thedetailrof inserting the tubing maybe neglecty ed at the timethe lament circuit is initially large filament current eausesjthe' seal to become energized whereupon the -heat generated bythe unduly hot. i y

Among the lobjects of the invention is to provideA a means which will Vensurerthe insertion off the tubing into. the reentrant stem at the time the tube is operated, therebyto provide a positive protection of the stem against high temperature, and,y in general, to assure the maintenance of certain portions of the envelope, subject to con-l siderable heat during operation., relatively cool.y

' For carrying out the objects off this 'invention,I -have devised an adaptor which directsa supply'o'f cooling fluid tothe heated parts simultaneously with the voperation of energizingfthe device.A The adaptor may take the form, in brief,

" of a combined air supply Vconduit and an electrivcal switch which is connected inl the filament energizing circuit. When the filament circuit is closed by moving the adaptor into position, connection is also made with an air supply manifold which serves to provide the'cooling medium.

Other objects and features will be apparent as the specification is perused in connection with Vthe accompanying drawing in which Fig. `1 illustrates the side elevational view of a power-tube `to which the invention has particular application; Fig. 2 is an enlarged elevational viewfof the adaptor which forms kthe subject matter' of` the presentinvention; Fig. 3 is aview partly in cross section of the tube, filament leads and reentrant stern, also showing `the adaptor kin detailwhile H Fig. .4`is a diagram ofl ay preferrediorm of electrical circuitoffor energizing the rfilament y In the drawing,` numeral 1 designatesa glass portion of an evacuatedenvelope, the lower end lofowhich` terminates in a cylindrical anode N2 and the upper end in a reentrant glassportion 3. Within the anode there is mounted, `in any suitable manner, a rectilinear iilamlentaryiy cath- 4 odeV (not shown)k and a rcylindrical grid or elecfr trostatic control ,member (not shown) positioned concentrically between the cathode and the anoder` YThe upper endof the lament is secured in position by means of twov conductors 4, 4

whichk are sealed in the press of the reentrant stem 3. The gridk member is rigidly mounted in the interior of the anode by means of a grid clamp 5 which embraces a glassl skirt portion 6 forming: an extension of thereentrantstem 3.:

The leading-,in conductors `for the filament terminate inthefflexible cables 7 'l` towhich 4are connected, metallic coupling membersv, 8. The

leading-in conductorfor the grid `preferably comprises a flexible stripy 9: secured tothe grid clamp and isi-usually taken from thefside o f` the enve-v lope. Vthrough a tubulation 10.vv In order. rigidly to spaceV the ,lamentconductors from ,originari-4 other -and to remove the `mechanical stressrat the press sea-l vdue'to the lever'effectn o .the conductors jat this point, thereisvprovided `a metallic cap 11 which ts overlthe upper end of the envelope and is secured thereto in-` ,any

y suitable manner, [for example by means of a cement.. 12. ,'Ifhe` cap 11 contains' a plurality of symmetricallyspaced apertures within which bushings 13' of insulating materialare tted; these bushings receive the:filamentj'fcables,'7, 7 as shown. 'l ,The cap als,9containsvuother, aper;

sol

tures, of which one maybe employed to receive a rigid tubingll of insulating material such as bakelitefrwhich tubing is employed for the purpose of directing a cooling uid against the lower portions yof Vthe lament conductors, the pinch seal Aand other.4 heated parts;r the remaining apertures may serve as a means of egress for the cooling fluid contained in the stem. The tubing 14 is secured rrigidly "to the cap member preferably by means of screw threads and a nut Y 15. lThe upper `end ofthe tubing is carried through the aperture to form an extension which terminates in a metallic ferrule or collar 16. The

adaptor proper consists in an annular nozzle member 17, preferably of bakelite, counterbored Vto'a limited depth snugly to receive the ferrule which is fitted aboutthe upright tubing 14. The

no y

adaptor preferably tapers off to a size as will wedge tightly within the flexible hose 18 which communicates with a source of cooling fluid (not shown) preferably under pressure. As explained hereinbefore, simultaneously with positioning the nozzle member on the tubing 14, it is desired to energize the filament circuit and for this purpose there is provided two contact strips 19, 19 preferably of copper, arranged diametrically across the counterbore and held in place by two terminals 20, 20. The terminals extend radially into the bore a distance to provide a stop or seat for the upper surface of the ferrule when the adaptor is moved into operating position. The latter position is clearly shown in Fig. 3 While the non-operating or inactive position of the adaptor is illustrated in Fig. 2.

One form of an electrical circuit arrangement which operates satisfactorily with the adaptor is shown in Fig. 4. The terminals 20, 20 are connected serially in a circuit which includes a source of electromotive force 2l and an electromagnet 22. The core 23 of the latter is attached to an armature 24 which makes and breaks a connection with a contact 25. The armature and contact are connected in a circuit preferably energized by a source 27 of alternating current preferably of commercial frequency and voltage, the latter being stepped down to a suitable Voltage by a transformer 26. The filament leads 7, 'l are connected across the secondary of the transformer, as shown. It will be evident that when the adaptor 17 is placed in position about the ferrule 16, the latter serves to complete the circuit through the terminals 20, 20 and battery 21, thus energizing the electromagnet. The armature 24 is then pulled upto complete circuit through the transformer 26 and the source of alternating current with the result that the filament is energized. The adaptor, in addition to causing the energization of the filament as described, also providesa connecting passage between the air supply hose 18 and the rigid tubing 14 positioned within the reentrant f stem 3. Consequently, a supply of cooling fiuid is directed against the stem and filament leads simultaneously with the act of energizing the filament. When the adaptor is removed manually to break the filament circuit, the continuity of the air passage is also broken. An important advantage in rigidly fixing' the tubing 14 to the cap 1l resides in the fact that the presence of such a Vtubing' is assured and the detail of inserting the member into the stem may be entirely dispensed with after the cap has lbeen positioned on the envelope.

WhatI claim as new anddesire to secure by Letters Patent of the United States, is:

1. Thermionic apparatus comprising the combination of an evacuated envelope containing an electrode adapted to be energized, said envelope being subjected to heating during the operation of the apparatus, a conduit for directing a cooling fluid against the heated portions of said envelope, said conduit being rigidly afiixed in position, an adaptor of annular form which is normally entirely separate from said conduit, said adaptor communicating at one end with a source of cooling fluid and at the other end is adapted to be placed in register with the opening of said conduit for supplying the conduit with cooling fluid and means whereby the adaptor also operates to control the energization of the electrode adapted to be energized.

2. Thermionic apparatus comprising the combination of an evacuated envelope containing an electrode adapted to be energized, said envelope being subjected to heating during the operation of the apparatus, a conduit for directing a cooling fluid toward theheated portions of said envelope, said conduit being rigidly affixed in position with respect to said envelope, an adaptor of annular form which is normally entirely separate from said conduit, said adaptor being flexibly joined at one end to a source of cooling fluid and at the other end is adapted to be placed in register with the opening of said conduit for supplying the conduit with cooling fluid and means whereby the adaptor also operates to control the energization of the electrode adapted to be energized, said means comprising an electrical con tact making device associated with the adaptor.

3. Thermionic apparatus comprising the combination of an evacuated envelope having a reentrant stem and containing an electrode adapted to be energized whereby the stem is subjected to heating during the operation of the apparatus, means for maintaining the stem relatively cool, said means comprising a conduit of insulating material positioned within the stem and terminating at the end remote from the stem in a metallic member, an adaptor having an aperture adapted to embrace the metallic member when the adaptor is in an operating position, a source of cooling fluid associated with the aperture, said adaptor being provided with contacts disposed on opposite sides thereof, the contacts being adapted to be connected in a circuit which controls an electrode energizing circuit so that when the adaptor is placed on the metallic member in an operating position, a circuit is completed through the said contacts thereby to cause energization of the electrode and to cause cooling fluid to flow from said source through the conduit thereby to maintain the stem relatively cool.

, MARCUS A. ACHESON. 

